This project investigates the relationship of non-medical drug use to ego functioning under varying setting conditions. The psychoanalytic model considers ego functions as those aspects of personality that govern adaptation. A system of classifying drug use patterns will be derived statistically from multiple dimensions of type (i.e., kind) and style (i.e., nature of involvement) of use. A multiple classification design will be used to compare ego functioning among resulting categories of drug users while simultaneously testing effects of phase: active street user vs. in crisis/seeking treatment vs. stabilized in treatment and 2) an index of social and person "costs" of drug use. Supplementary analyses will also consider differences in functioning related to 1) choice of treatment (private, methadone, or drug free) and 2) to determine variability of functioning and relative degree of impairment within categories under different conditions and in relation to "cost"; and 3) to test theoretical hypotheses as to the nature of adaptive disturbance in drug dependence. Data for the criterion measures of ego function will be derived from clinical interview and psychometric testing of an estimated 240 subjects. Addition in depth data from ongoing psychotherapy will be collected for a subset of the sample. Dynamically oriented clinicians will apply the findings of this study to patient care planning; research on treatment outcome, prediction, and prevention will be strongly faciliated by an integrated system of classification which combines behavioral, personality, and setting factors.